齒輪套機械加工工藝及鏜φ30內孔夾具設計
齒輪套機械加工工藝及鏜30內孔夾具設計,齒輪套機械加工工藝及鏜30內孔夾具設計,齒輪,機械,加工,工藝,30,夾具,設計
機械加工工序卡產(chǎn)品型號零件圖號產(chǎn)品名稱齒輪套零件名稱齒輪套共2頁第1頁 車間工序號工序名稱材 料 牌 號3粗鏜毛 坯 種 類毛坯外形尺寸每毛坯可制件數(shù)每 臺 件 數(shù)鍛件1146711設備名稱設備型號設備編號同時加工件數(shù)臥式鏜床T681夾具編號夾具名稱切削液 專用夾具工位器具編號工位器具名稱工序工時 準終單件9.33工步號工 步 內 容工 藝 裝 備主軸轉速切削速度進給量背吃刀量進給次數(shù)工步工時r/minm/minmm/rmm機動輔助1粗銑30內孔,單邊加工余量為1.3mm 專用夾具,鏜刀,內徑百分深度百分尺500 45.550.741.319.33s 設 計(日 期) 審 核(日期) 標準化(日期) 會 簽(日期)標記處數(shù)更改文件號簽 字 日 期標記處數(shù)更改文件號簽 字 日 期2016.1.27太原理工大學機械加工工序卡產(chǎn)品型號零件圖號產(chǎn)品名稱齒輪套零件名稱齒輪套共2頁第1頁 車間工序號工序名稱材 料 牌 號8半精鏜毛 坯 種 類毛坯外形尺寸每毛坯可制件數(shù)每 臺 件 數(shù)鍛件1116411設備名稱設備型號設備編號同時加工件數(shù)臥式鏜床T681夾具編號夾具名稱切削液專用夾具 工位器具編號工位器具名稱工序工時 準終單件工步號工 步 內 容工 藝 裝 備主軸轉速切削速度進給量背吃刀量進給次數(shù)工步工時r/minm/minmm/rmm機動輔助1半精鏜30內孔,雙邊加工余量為1mm,鏜倒角。 專用夾具,鏜刀,內徑百分深度百分尺80075.40.370.5112.17s 設 計(日 期) 審 核(日期) 標準化(日期) 會 簽(日期)標記處數(shù)更改文件號簽 字 日 期標記處數(shù)更改文件號簽 字 日 期2016.1.27 機械加工工藝過程卡片產(chǎn)品型號零件圖號產(chǎn)品名稱齒輪套零件名稱齒輪套共1頁第1頁材 料 牌 號 45鋼毛 坯 種 類鍛件毛坯外形尺寸11467每毛坯可制件數(shù)1每 臺 件 數(shù)1備 注 工 序 號工 名序 稱工 序 內 容 車 間 工 段設 備工 藝 裝 備 工 時 /s 準終 單件1鍛造2時效處理3粗鏜粗鏜30內孔,雙邊加工余量為3mm。T68臥式鏜床內徑百分尺、深度百分尺、專用夾具、硬質合金鏜刀9.334粗車粗車63外圓,雙邊加工余量為3mm。粗車齒輪右端面,加工余量為1.5mm。C620-1臥式車床硬質合金車刀、游標卡尺、外徑千分尺、專用夾具25.45粗鏜粗鏜32內孔,雙邊加工余量為6mm,鏜倒角。T68臥式鏜床內徑百分尺、深度百分尺、專用夾具、硬質合金鏜刀10.36粗車粗車40端面,齒輪左端面,加工余量為1.5mm。粗車42外圓,雙邊加工余量為3mm。粗車40外圓,雙邊加工余量為2mmC620-1臥式車床硬質合金車刀、游標卡尺、外徑千分尺、專用夾具77.957拉鍵槽拉鍵槽L6110臥式拉床鍵槽拉刀、專用夾具、208半精鏜 半精鏜30內孔,雙邊加工余量為1mm,鏜倒角。T68臥式鏜床內徑百分尺、深度百分尺、專用夾具、硬質合金鏜刀12.179半精車 半精車63外圓,雙邊加工余量為1mm。半精車齒輪右端面,加工余量為0.5mm。車倒角。C620-1臥式車床硬質合金車刀、游標卡尺、外徑千分尺、專用夾具16.210半精車半精車40端面,齒輪左端面,加工余量為0.5mm。半精車42外圓,雙邊加工余量為1mm。半精車40外圓,雙邊加工余量為1mm。車溝槽,倒角。C620-1臥式車床硬質合金車刀、游標卡尺、外徑千分尺、專用夾具26.8711鉆孔鉆8.5孔Z518立式鉆床游標卡尺、專用夾具、直柄麻花鉆3.912滾齒滾齒Y3150滾齒機公法線百分尺、高速鋼單頭滾刀、專用夾具96.9713淬火淬火14磨削磨削40,42外圓,雙邊加工余量為0.4mm。M114W萬能外圓磨床砂輪、專用夾具、6515磨削磨削30內孔,雙加工余量為0.4mmM2110砂輪、專用夾具6316終檢 設 計(日 期) 校 對(日期) 審 核(日期) 標準化(日期) 會 簽(日期)2016.1.27標記處數(shù)更改文件號簽 字 日 期標記處數(shù)更改文件號簽 字 日 期 課 程 設 計 說 明 書課程名稱:機械制造技術基礎課程設計設計題目:齒輪套零件的機械加工工藝規(guī)程及工藝裝備設計 姓 名:專業(yè)班級:指導教師:2016年1月27日理工大學機械工程學院3太原理工大學課程設計說明書目錄摘要3第一章 緒論4第二章 齒輪套的加工工藝規(guī)程規(guī)定52.1 零件的分析52.1.1零件的作用52.1.2零件的工藝分析52.2 確定生產(chǎn)類型62.3 確定毛坯62.3.1 確定毛坯種類62.3.2 確定鑄造加工量及形狀62.3.3 繪制毛坯圖82.4 工藝規(guī)程設計82.4.1 選擇定位基準82.4.2 制定工藝路線92.4.3 選擇加工設備和工藝設備102.4.4 機械加工余量、工序尺寸及公差的確定112.5 確定切削用量及基本工時132.5.1粗鏜30內孔132.5.2粗車67外圓及齒輪右端面132.5.3粗鏜32內孔162.5.4 粗車左端面及46.4外圓、43.4外圓172.5.5拉鍵槽182.5.6半精鏜30內孔192.5.7 半精車63202.5.8半精車43.4,41.4外圓,端面212.5.9鉆8.5孔232.5.10滾齒242.5.11 磨削外圓252.5.12 磨削內孔262.6 本章小結27第三章 鏜30內孔夾具設計283.1設計要求283.2 夾具設計283.2.1 定位基準的選擇283.2.2 切削力及夾緊力的計算283.3 定位誤差的分析31參考文獻33致謝34摘要本文是對齒輪套零件加工應用及加工的工藝性分析,主要包括對零件圖的分析、毛坯的選擇、零件的裝夾、工藝路線的制訂、刀具的選擇、切削用量的確定、加工工藝文件的填寫。選擇正確的加工方法,設計合理的加工工藝過程。此外還對軸承座零件的一道工序的加工設計了專用夾具.機床夾具的種類很多,其中,使用范圍最廣的通用夾具,規(guī)格尺寸多已標準化,并且有專業(yè)的工廠進行生產(chǎn)。而廣泛用于批量生產(chǎn),專為某工件加工工序服務的專用夾具,則需要各制造廠根據(jù)工件加工工藝自行設計制造。本論文夾具設計的主要內容是設計齒輪套齒輪上加工30孔的鏜床夾具設計。太原理工大學課程設計說明書第一章 緒論機械制造業(yè)是制造具有一定形狀位置和尺寸的零件和產(chǎn)品,并把它們裝備成機械裝備的行業(yè)。機械制造業(yè)的產(chǎn)品既可以直接供人們使用,也可以為其它行業(yè)的生產(chǎn)提供裝備,社會上有著各種各樣的機械或機械制造業(yè)的產(chǎn)品。我們的生活離不開制造業(yè),因此制造業(yè)是國民經(jīng)濟發(fā)展的重要行業(yè),是一個國家或地區(qū)發(fā)展的重要基礎及有力支柱。從某中意義上講,機械制造水平的高低是衡量一個國家國民經(jīng)濟綜合實力和科學技術水平的重要指標。齒輪套零件加工工藝及夾具設計是在學完了機械制圖、機械制造技術基礎、機械設計、機械工程材料等的基礎下,進行的一個全面的考核。正確地解決一個零件在加工中的定位,夾緊以及工藝路線安排,工藝尺寸確定等問題,并設計出專用夾具,保證尺寸證零件的加工質量。本次設計也要培養(yǎng)自己的自學與創(chuàng)新能力。因此本次設計綜合性和實踐性強、涉及知識面廣。所以在設計中既要注意基本概念、基本理論,又要注意生產(chǎn)實踐的需要,只有將各種理論與生產(chǎn)實踐相結合,才能很好的完成本次設計。本次設計水平有限,其中難免有缺點錯誤,敬請老師們批評指正。第二章 齒輪套的加工工藝規(guī)程規(guī)定2.1 零件的分析 2.1.1零件的作用題目所給的零件是齒輪套。齒輪套是屬于齒輪的一種。齒輪套的用途很廣泛,是各種機械設備零件中的重要零件,例如機床,飛機,輪船等等都要使用齒輪套。齒輪套的主要作用是調整機構的轉速和力矩,傳遞動力;改變動力輸出的旋轉方向等。2.1.2零件的工藝分析圖2.1 齒輪套零件圖零件的材料為45鋼,鍛造性能和切削加工性能優(yōu)良。以下是齒輪套需要加工的表面以及加工表面之間的位置要求:(1) 中心圓孔,32,30。(2) 端面與中心孔有垂直度(4) 外圓表面與中心孔30有位置關系。由上面分析可知,可以先粗加工加工齒輪套內孔,然后以此作為基準加工30孔,再以孔為基準采用專用夾具進行精加工,并且保證位置精度要求。再根據(jù)各加工方法的經(jīng)濟精度及機床所能達到的位置精度,并且此齒輪套零件沒有復雜的加工曲面,所以根據(jù)上述技術要求采用常規(guī)的加工工藝均可保證。2.2 確定生產(chǎn)類型已知此軸承座零件的生產(chǎn)類型屬于中批量生產(chǎn),所以初步確定工藝安排為:加工過程劃分階段;工序應當分散;加工設備以通用設備為主,大量采用專用工裝。2.3 確定毛坯 2.3.1 確定毛坯種類零件材料為45鋼??紤]零件結構簡單,生產(chǎn)批量大,毛坯精度要求不高,從高效低成本綜合考慮,選擇模鍛成型鍛造毛坯。 2.3.2 確定鑄造加工量及形狀查機械制造工藝設計簡明手冊表2.2-25確定加工余量及鍛件毛坯尺寸如下表:表2.1 毛坯尺寸零件尺寸單面加工余量鍛件尺寸110211419223403.246.4422.246.43022663267查機械制造工藝設計簡明手冊表2.2-13 確定毛坯尺寸偏差如下表:表1.2 毛坯尺寸偏差鍛件尺寸偏差114114-0.61.22323-0.20.846.4464-0.51.12626-10.46767-0.51.1 2.3.3 繪制毛坯圖圖2.2 齒輪套毛坯圖2.4 工藝規(guī)程設計 2.4.1 選擇定位基準 1)粗基準的選擇以零件的內孔為主要的定位粗基準,以左端面輔助粗基準。2)精基準的選擇考慮要保證零件的加工精度和裝夾準確方便,依據(jù)“基準重合”原則和“基準統(tǒng)一”原則,以加工后的30為主要的定位精基準,以已加工的右平面輔助的定位精基準。3)在鉆孔時以鍛造的孔一側作輔助定位基準2.4.2 制定工藝路線根據(jù)零件的幾何形狀、尺寸精度及位置精度等技術要求,以及加工方法所能達到的經(jīng)濟精度,在生產(chǎn)綱領已確定的情況下,可以考慮采用各種機床配以專用夾具,并盡量使工序集中來提高生產(chǎn)率。除此之外,還應當考慮經(jīng)濟效果,以便使生產(chǎn)成本盡量下降。選擇零件的加工方法及工藝路線方案如下:表2.3 工藝路線工序一鍛造工序二時效處理工序三粗鏜30內孔工序四粗車齒輪右端面,粗車63外圓工序五粗鏜32內孔,鏜倒角工序六粗車40端面,粗車齒輪左端面,粗車42外圓,粗車40外圓工序七拉鍵槽工序八半精鏜30內孔,鏜倒角工序九半精車齒輪右端面,半精車63外圓,車倒角工序十 半精車40端面,半精車齒輪右端面,半精車42外圓,半精車40外圓,車倒角、溝槽工序十一鉆8.5孔工序十二滾齒工序十三淬火工序十四磨削42外圓,磨削40外圓工序十五磨削30內孔工序十六終檢入庫2.4.3 選擇加工設備和工藝設備1)機床的選擇工序四、六、九、十、采用C620-1臥式車床工序三、五、八采用T68臥式鏜床工序十一采用Z3025立式鉆床工序七采用L6110臥式拉床工序十二采用Y3150滾齒機工序十四采用M114W萬能外圓磨床工序十五采用M2110內圓磨床2)選擇夾具該齒輪套的生產(chǎn)綱領為大批生產(chǎn),所以采用專用夾具。3)選擇刀具在車床上加工的各工序,采用硬質合金車刀即可保證加工質量,鉆床加工采用高速鋼復合鉆頭,零件加工內孔較小,使用硬質合金鏜刀加工。4)選擇量具加工的孔均采用極限量規(guī)。5)其他對垂直度誤差采用千分表進行檢測,對角度尺寸利用專用夾具保證,其他尺寸采用通用量具即可。2.4.4 機械加工余量、工序尺寸及公差的確定1)圓柱面工序尺寸的確定:表2.2 圓柱面工序尺寸加工表面加工內容單邊加工余量精度等級工序尺寸表面粗糙度工序余量最小最大32粗鏜3IT123212.533.10530粗鏜1.3IT1228.66.31.51.605半精鏜0.5IT829.63.20.4350.5115磨削0.2IT7301.60.18350.210540粗車1IT1241.46.311.125半精車0.5IT940.43.20.3750.531磨削0.2IT8400.80.1690.212542粗車1.5IT1243.46.31.51.625半精車0.5IT942.43.20.3750.531磨削0.2IT8420.80.1690.212563粗車1.5IT12646.31.51.625半精車0.5IT9633.20.3750.552) 軸向工序尺寸的確定表2.3 軸向工序尺寸加工內容加工余量基本尺寸經(jīng)濟精度粗車齒輪右端面1.5112.5IT12粗車40端面1.5111IT12粗車齒輪左端面1.520IT12半精車齒輪右端面0.5110.5IT9半精車40端面0.5110IT9半精車齒輪左端面0.519IT92.5 確定切削用量及基本工時 2.5.1粗鏜30內孔所選用刀具為YT5硬質合金鏜刀,選用T68臥式鏜床。1)確定切削深度ap ap=1.3mm2)確定進給量f根據(jù)實用機械加工工藝手冊表9-145,查得粗鏜時,選用硬質合金刀頭,加工材料為鋼時:v=4060m/min f=0.31.0mm/r按機床的進給量(表4.221),選擇, f=0.74mm/r3)確定機床轉速n n=500r/min=8.33r/s4)計算基本工時選鏜刀的主偏角kr=45,則L1=3.5mm,L=54mm,L2=L3=0,f=0.74mm/r ,n=8.33r/s則: T=3.5+540.748.33=9.33S 2.5.2粗車67外圓及齒輪右端面 本工序為粗車。已知加工材料為45鋼,b=670Mpa,鍛件,有外皮,機床為C620-1臥式車床,工件裝在專用夾具中。確定粗車外圓67外圓的切削用量 所選刀具為YT5硬質合金可轉位車刀。根據(jù)切削用量簡明手冊第一部分表1.1,由于C620-1機床中心高為200mm(表1.30),故選擇刀桿尺寸BH=16mm 25mm,刀片厚度為4.5mm。根據(jù)表1.3,選擇車刀形狀為卷屑槽帶倒菱形前刀面,前角0=12,后角0=6,主偏角0=90,副偏角0=10,刃傾角0=0,刀尖圓弧半徑r=0.8mm。1) 確定切削深度ap 最大單邊加工余量為2.2mm,可在一次走刀完成,故粗加工余量取1.5mm,2) 確定進給量f 根據(jù)表切削用量簡明手冊表1.4,在粗車鋼料,刀桿尺寸為16mm 25mm,ap3mm,工件直徑在60100mm時, f=0.40.7mm/r 按C620-1車床說明書選擇 f=0.55mm/r 確定的進給量尚需滿足車床進給機構強度的要求,故需進行校驗。 根據(jù)C620-1車床說明書,其進給機構允許的進給力Fmax=3530N, 根據(jù)表切削用量簡明手冊1.21,但鋼料b=570670Mpa,ap2mm,f0.75mm,r=45,v=65m/s(預計)時,進給力F=760N, Ff的修正系數(shù)為k0Ff=1.0,ksFf=1.0,krFf=1.17(表1.292),故實際進給力Ff=7601.17=889.2N 由于切削時進給力小于機床進給機構允許的進給力,故所選的f=0.65mm/r可用。3) 選擇車刀磨鈍標準及耐用度 根據(jù)切削用量簡明手冊表1.9,車刀后刀面最大磨損量取為1mm,可轉位車刀耐用度T=30min。4)確定切削速度v 切削速度v可根據(jù)公式計算,也可直接由表中查出?,F(xiàn)采用查表法確定切削速度。 根據(jù)切削用量簡明手冊表1.10,但用YT15硬質合金車刀加工b=600700Mpa鋼料,ap3mm,f0.75mm/r,切削速度v=109m/min。 切削速度的修正系數(shù)ksv=0.8,ktv=0.65,krv=0.81,kTv=1.15,kMv=kkv=1.0(均見表1.28),故 V=1090.80.650.811.15m/min=52.8m/min n=1000vd=100052.567=250.85r/min, 按C620-1機床轉速(表4.2-8),選擇 n=230r/min 此時實際切削速度VC=48.41m/min。5)校驗機床功率 由切削用量簡明手冊表1.24,但b=580970Mpa,HBS=166277,ap2.0mm,f0.6mm/r,v57m/min時,Pc=1.7kw 切削功率的修正系數(shù)krPc=1.17,k0Pc=kMpc=kKPc=1.0,kTPc=1.13,kSPc=0.8,ktPc=0.65(表1.28),故實際切削時的功率為: Pc=0.72KW根據(jù)切削用量簡明手冊表1.30,但n=230r/min,機床主軸允許功率PE=5.9KW,PcPE,故所選的切削用量可在C620-1機床上進行。 最后決定的切削用量為 ap=1.5mm,f=0.55mm/r,n=230r/min,v=48.4m/min確定粗車外圓46.4,端面的切削用量 采用車外圓67的刀具加工這些表面。加工余量皆可一次走刀切除,車外圓46.4的f=0.55mm/r,ap=1.5mm,主軸轉速與車外圓67相同。1.2 基本時間 確定粗車外圓67的基本時間 根據(jù)表6.2-1,車外圓基本時間為Tj1=Lfni=l+l1+l2+l3fni 式中:l=23mm,l1=0,l2=4,l3=0,i=1,f=0.55r/min,n=3.83mm/r, 則Tj1=23+40.553.83=12.82s確定粗車67端面的時間 Tj2=Lfni,L=d-d12+l1+l2+l3 式中: d=67mm。d1=26mm。l1=2mm,l2=4mm,l3=0,f=0.55mm/r,i=1,n=3.38r/s,則Tj2=20.5+2+43.830.55=12.58s2.5.3粗鏜32內孔所選用刀具為YT5硬質合金鏜刀。1)確定切削深度ap ap=3mm2)確定進給量f根據(jù)實用機械加工工藝手冊表9-145,查得粗鏜時,選用硬質合金刀頭,加工材料為鋼時: V=4060m/min f=0.31.0mm/r按機床的進給量(表4.221),選擇, f=0.74mm/r3)確定機床轉速n n=500r/min=8.33r/s4)計算基本工時選鏜刀的主偏角kr=45,則L1=3.5mm,L=60mm,L2=0,f=0.74mm/r, n=8.33r/s則: T=3.5+600.748.33 10.3 2.5.4 粗車左端面及46.4外圓、43.4外圓本工序仍為粗車,已知條件與工序一相同,車端面,車外圓采用與工序一相同的可轉位車刀,采用工序一確定切削用量的方法,得本工序的切削用量及基本時間,得下表:表2.4 切削余量工步ap(mm)f(mm/r)V(m/s)n(r/s)T(s)粗車64端面1.50.550.813.837.74粗車64.4端面1.50.550.493.8312.53粗車46.4外圓1.50.550.563.8345.10粗車43.4外圓10.550.523.8312.582.5.5拉鍵槽根據(jù)實用機械加工工藝手冊表7-160,選寬刀體鍵槽拉刀,根據(jù)機械制造工藝設計簡明手冊,選L6110型臥式內拉床。 基本時間T=ZbLk1000VfzZ 式中: V=0.06m/s(3.6m/min) zb 單面余量2.7mm L 拉削表面長度,110mm; 考慮校準部分的長度系數(shù),取1.2; k 考慮機床返回行程系數(shù),取1.4 ; fa 拉刀每齒進給量; Z 拉刀同時工作齒數(shù),Z=l/p; P 拉刀齒距。 P=(1.25-1.5)sqrt110=1.35sqrt110=14mm拉刀同時工作齒數(shù)z=l/14=80/146 T=2.71101.21.4/(10003.60.066)=0.33min2.5.6半精鏜30內孔 所選用刀具為YT15硬質合金鏜刀。1)確定切削深度ap ap=0.5mm2)確定進給量f根據(jù)實用機械加工工藝手冊表9-145,查得半精鏜時,選用硬質合金刀頭,加工材料為鋼時: V=80120m/min f=0.20.8mm/r按機床的進給量(表4.221),選擇, f =0.37mm/r3)確定機床轉速n n=800r/min=13.33r/s4)計算基本工時選鏜刀的主偏角kr=45,則L1=3.5mm,L=52.5mm L2=4mm,L3=0,f=0.37mm/r, n=13.33r/s則: T=3.5+52.5+40.3713.33 12.17 2.5.7 半精車63 外圓及齒輪右端面 本工序為半精加工,已知條件與粗加工工序相同。1) 確定半精車外圓67外圓的切削用量 所選刀具為YT15硬質合金可轉位車刀。車刀形狀,刀桿尺寸以及刀片厚度均與粗車相同。根據(jù)表1.3,車刀幾何形狀為0=12,0=8,0=90,0=5,n=0,r=0.5mm。2) 確定切削深度ap ap=0.5mm3) 確定進給量 根據(jù)切削用量簡明手冊表1.6及C620-1機床進給量(表4.2-9),選擇f=0.3mm/r,由于是半精加工,切削力較小,所以不需要進行車床進給量強度校核。4) 選擇選擇車刀磨鈍標準及耐用度 根據(jù)切削用量簡明手冊表1.9,車刀后刀面最大磨損量取為0.4mm,可轉位車刀耐用度T=30min。5) 確定切削速度V 根據(jù)表根據(jù)切削用量簡明手冊表1.10,但用YT15硬質合金車刀加工b= 600700Mpa鋼料,ap1.4mm,f0.38mm/r,切削速度V=156m/min。 切削速度的修正系數(shù)krv=0.81,kTv=1.15,其余修正系數(shù)為1,均見表1.28),故 V=1380.811.15m/min=145.5m/min n=1000vd=1000145.364=722.66r/min, 按C620-1機床轉速(機械制造工藝設計簡明手冊表4.2-8),選擇 n=600r/min=10r/s 此時實際切削速度Vc=120.64m/min。 最后決定的切削用量為 ap=0.5mm,f=0.3mm/r,n=600r/min=10r/s,v=120.64m/min=2.01m/s6) 基本時間 確定半精車車外圓64的基本時間 根據(jù)表6.2-1,車外圓基本時間為Tj1=Lfni=l+l1+l2+l3fni 式中:l=19.5mm,l1=0,l2=4,l3=0,i=1,f=0.3r/min,n=10r/s, 則Tj1=19.5+4100.3=7.83s確定半精車64端面的時間 Tj2=Lfni,L=d-d12+l1+l2+l3 式中: d=64mm。d1=26mm。l1=2mm,l2=4mm,l3=0,f=0.3mm/r,i=1,n=10r/s,則Tj2=19.4+2+4100.3=8.4s2.5.8半精車43.4,41.4外圓,端面1)采用半精車外圓63的刀具加工這些表面。車外圓43.4,41.4的ap=0.5mm,f=0.33mm/r,n=1075.59r/min。按C620-1機床轉速(機械制造工藝設計簡明手冊表4.2-8),選擇:n=960r/min=16r/s2)最后確定 ap=0.5mm,f=0.3mm/r,n=960r/min=16r/s,v=103.69m/min=1.73m/s3)確定半精車車外圓43.4的基本時間 根據(jù)表6.2-1,車外圓基本時間為Tj1=Lfni=l+l1+l2+l3fni 式中: l=69.5mm,l1=0,l2=4,l3=0,i=1,f=0.3mm/r,n=16r/s, 則Tj1=69.5+4160.3=15.31s4)確定半精車41.5端面的時間 Tj2=Lfni,L=d-d12+l1+l2+l3 式中: d=41.5mm。d1=26mm。l1=2mm,l2=4mm,l3=0,f=0.3mm/r,i=1,n=10r/s,則Tj2=7.75+2+4160.3=2.86s5) 確定半精車車外圓41.5的基本時間 根據(jù)表6.2-1,車外圓基本時間為Tj1=Lfni=l+l1+l2+l3fni 式中: l=22mm,l1=0,l2=4,l3=0,i=1,f=0.3r/mm,n=16r/s, 則Tj1=22+4160.3=5.41s6)確定半精車63端面的時間 Tj2=Lfni,L=d-d12+l1+l2+l3 式中: d=63mm。d1=43.4mm。l1=2mm,l2=4mm,l3=0,f=0.3mm/r,i=1,n=10r/s,則Tj2=9.8+2+4160.3=3.29s7)車溝槽,車倒角 選用高速鋼成形切槽刀,采用手動進給,主軸轉速n=40r/min,切削速度v=0.14m/s。2.5.9鉆8.5孔本工序為鉆孔,刀具選用高速鋼復合鉆頭,直徑8.5。1)確定進給量f 由于孔徑和深度都很小,宜采用手動進給。2)選擇鉆頭磨鈍標準及耐用度 根據(jù)切削用量簡明手冊表2.12,鉆頭后刀面最大磨損量取為0.8mm;耐用度T=25min。3)確定切削速度v 由表2.14,b=670MPa的45鋼加工性屬五類。根據(jù)表2.7,暫定進給量f=0.25mm/r。由表2.13查得v=14m/min,n=524.5r/min。根據(jù)Z518立式鉆床機床說明書選擇主軸實際完成轉速。4)基本時間的確定 L=6.7mm,L1=3mm,L2=0mm T=6.7+30.25449.4=3.9S2.5.10滾齒 1) 選用標準的高速鋼單頭滾刀,模數(shù)m=1.5,直徑63mm,可以采用一次走刀切至全深。工件齒面要求表面粗糙度為Ra1.6m,根據(jù),切削用量簡明手冊表4.2,選擇工件每轉滾刀軸向進給量fa=0.50.8mm/r。按Y150型滾齒機進給量表(表4.2-51),選fa=0.7mm/r。2)計算切削速度v = 式中Cv=364,T=240min,fa=0.7mm/r,m=1.5mm,mv=0.5,yv=0.85,xv=-0.5,kv=0.64 V =3642400.50.70.851.5-0.5 0.64= 24.9m/min n=125r/min根據(jù)Y3150型滾齒機主軸轉速(表4.2-50),選n=135r/min=2.25r/s。 實際切削速度為 v=0.45m/s加工時的切削功率Pc=0.091kw,Y3150型滾齒機的主電機PE=3kw。因PCPE,顧所選擇的切削用量可在該機床上使用。3) 基本時間根據(jù)表6.2-13,用滾刀滾圓柱齒輪的基本時間B=19mm, =0,z=50,q=1,n=2.25r/s,fa=0.7mm/r,則La1=16.18mm, fa=3mm, T =(19+16.18+3)4012.250.7 = 96.97s2.5.11 磨削外圓 1)選擇砂輪。根據(jù)機械制造工藝設計簡明手冊第三章中各表選擇磨具,結果為:ZA46JV6P30040127其含義為:磨輪磨料為鉻剛玉,為了防止粒度過小而磨輪堵塞,所以選用為粒度為46,硬度為軟3級。 平型砂輪,其尺寸為16640(DdH)。2)切削用量的選擇 根據(jù)實用機械加工工藝手冊表10-9,查得:工件速度V=2040m/min,縱向進給量fa=16mm/r,工作臺單行程磨削深度fr=0.0049mm/st 3) 根據(jù)機械制造工藝設計簡明手冊表42-30,選用M114W萬能外圓磨床。4) 基本時間 根據(jù)機械制造工藝設計簡明手冊表6.2-8, T=ZbLknfafr磨削40外圓時,L=22mm,Zb=0.2mm,k=1.4,n=300r/min, fa=16mm/r, fr=0.0049mm/st T1=220.21.4300160.0049 =0.26min=15.71s磨削42外圓時,L=69mm,Zb=0.2mm,k=1.4,n=300r/min, fa=16mm/r, fr=0.0049mm/stT2=690.21.4300160.0049 =0.82min=49.29s2.5.12 磨削內孔1)選擇砂輪。 磨輪磨料為鉻剛玉,為了防止粒度過小而磨輪堵塞,所以選用為粒度為46,硬度為軟3級。 根據(jù)機械制造工藝設計簡明手冊表3.2-8、3.2-9查得內圓磨輪直徑d=25mm,B=3240mm。2)切削用量的選擇 根據(jù)實用機械加工工藝手冊表10-15,查得:工件速度V=2540m/min,縱向進給量fa=16mm/r,工作臺單行程磨削深度fr=0.0030mm/st3) 根據(jù)機械制造工藝設計簡明手冊表42-31,選用M2110內圓磨床。4) 基本時間 根據(jù)機械制造工藝設計簡明手冊表6.2-8, T=ZbLknfafr磨削30內孔時,L=54mm,Zb=0.2mm,k=1.4,n=300r/min, fa=16mm/r, fr=0.0030mm/st T1=540.21.4300160.0030 =1.05min=63s最后,將以上各個工序切削用量、工時定額的計算結果,連同其它加工數(shù)據(jù),一起填入機械加工工藝過程綜合卡中。2.6 本章小結本章節(jié)主要從零件的結構和外型入手分析,從而得出設計毛坯的依據(jù)。再查閱有關資料,設計出零件加工的毛坯。在工藝規(guī)程的制定上,將兩種方案進行比較,選取一個最佳方案來。在計算每一步的切削用量時,先選用刀具和機床,再查閱資料找出進給量,由它算出機床所需的轉速,翻閱機床手冊選一個最接近它的一值。算切削速度、機動時間等。第三章 鏜30內孔夾具設計3.1設計要求 為了提高勞動生產(chǎn),保證加工質量,降低勞動強度,需要設計專用夾具。下面即為鏜床夾具(鏜30內孔)的專用夾具,本夾具將用于T68臥式鏜床。本夾具無嚴格的技術要求,因此,應主要考慮如何提高勞動生產(chǎn)率,降低勞動強度,精度不是主要考慮的問題。3.2 夾具設計 3.2.1 定位基準的選擇本夾具如圖所示,是工序一、六,即用T68臥式鏜床加工30內孔,采用專用夾具進行加工。該零件加工精度要求最高的是中間30 的內孔,且其余加工面都與該孔有關,因此在該孔時以32內孔為定位基準,保證同軸度。工序一,先對30內孔進行粗加工。到工序六時,零件的兩個端面已經(jīng)粗加工過,選左側端面和32內孔為定位基準,定位中選用了一個A型可換定位銷和一支承板限制零件的自由度,可換定位銷直徑為26,為一個短銷,可以限制兩個自由度,夾具側板限制三個自由度。3.2.2 切削力及夾緊力的計算 刀具:硬質合金鏜刀YT5。 根據(jù)切削用量簡明手冊表1.29查得:主切削力Fc=CFcapXFcfyFcVnFckFc徑向切削力Fp=CFpapXFpfyFpVnFpkFp軸向力Ff=CFfapXFffyFfVnFfkFf 其中CFc=2795,XFc =1.0, yFc=0.75, nFc=-0.15; CFp=1940, XFp=0.9, yFp=0.6, nFp=-0.3;CFf =2880, XFf=1.0, yFf=0.5, nFf=-0.4;ap=1.5mm,f=0.74mm/r,V=500r/min。 可得: Fc=27951.51.00.740.75500-0.5=1316.9N Fp =19401.50.90.740.75500-0.3500=361.5N Ff=22801.51.00.740.5500-0.4=244.9N 根據(jù)切削用量簡明手冊1.29-1、1.29-2查得修正系數(shù)k 得: Fc=1316.91.0220.94=1265N Fp=361.51.0420.77=290N Ff=244.91.031.11=280N根據(jù)工件受力切削力、夾緊力的作用情況,找出在加工過程中對夾緊最不利的瞬間狀態(tài),按靜力平衡原理計算出理論夾緊力。最后為保證夾緊可靠,再乘以安全系數(shù)作為實際所需夾緊力的數(shù)值,即:Wk=WK 式中:Wk-實際所需夾緊力 K-安全系數(shù) K-在一定條件下,由靜力平衡計算出的理論夾緊力其中,K=K0K1K2K3K3K5K6 K0考慮工件材料及加工余量均勻性的基本安全系數(shù)K1加工性質K2刀具鈍化程度K3切削特點、K4夾緊力的穩(wěn)定性K5手動夾緊時的手柄位置K6僅有力矩時工件回轉時工件與支承面接觸的情況根據(jù)機床夾具設計手冊表1-2-1可得:主切削力FcFC安全系數(shù): K0=1.2,K1=1.2,K2=1.0, K3 =1.0,K4=1.3,K5=1.0,K6 =1.0 徑向切削力Fc安全系數(shù):K0=1.2,K1=1.2,K2=1.0, K3 =1.0,K4=1.3,K5=1.0,K6 =1.0軸向力Ff安全系數(shù): K0=1.2,K1=1.2,K2=1.0, K3 =1.0,K4=1.3, K5=1.0,K6 =1.0所以,可以計算出: Kc=1.21.21.01.01.31.01.0=1.872 Kp=1.21.21.41.01.31.01.0=2.62 Kf=1.21.21.61.01.31.01.0=2.99若安全系數(shù)K的計算結果小于2.5時,取K=2.5。 所以,WC =2.51265=3162.5N WP=2902.62=760N Wf=2802.99=837N鏜孔時的主切削力由定位面和夾緊力產(chǎn)生的摩擦力平衡,f1,f2 分別為夾具定位面及夾緊面上的摩擦系數(shù),F(xiàn)=3162.5/0.5=6325N定位面和夾緊力產(chǎn)生的摩擦力遠大于鏜孔產(chǎn)生的徑向切削力,鏜床側板作為軸向力的支承。3.3 定位誤差的分析 為了滿足工序的加工要求,必須使工序中誤差總和等于或小于該工序所規(guī)定的尺寸公差:e基+T 其中,e定= e不+e基鏜孔時,工序基準與定位基準重合,因此 e不=0定位銷與孔配合公差為H7/h6,定位銷水平放置時:e基=1/2(TD+Td+Cmin)=1/2Cmax=0.022 按加工經(jīng)濟精度查表得=0.13 e定+=0.152T=0.21從以上的分析可見,所設計的夾具能滿足零件的加工精度要求。 圖3.1 齒輪套鏜孔裝配圖主視圖圖3.2 齒輪套鏜孔裝配圖俯視圖圖3.3 齒輪套鏜孔裝配圖左視圖參考文獻1曾志新,呂明.機械制造技術基礎M.武漢理工出版社,2001.72李益民.機械制造工藝設計簡明手冊M.機械工業(yè)出版社,1993.43艾興,肖詩綱.切削用量簡明手冊M.第3版,機械工業(yè)出版社,1997.84馬麟.畫法幾何與機械制圖M.高等教育出版社,2011.95王光斗,王春福.機床夾具設計手冊M.上??茖W技術出版社,2000.16陳均宏.實用機械加工工藝手冊M.機械工業(yè)出版社,1996.127朱耀祥,蒲林祥.現(xiàn)代夾具設計手冊M.第3版,機械工業(yè)出版社,2009.108廖念釗,古瑩菴,莫雨松.互換性與技術測量.第六版,中國質檢出版社,2012致謝在這次課程設計的撰寫過程中,我得到了許多人的幫助。首先,我眼感謝指導老師在課程設計上給予我的指導、提供給我的支持和幫助,只是我能順利完成這次報告的主要原因,更重要的是老師幫我解決了許多技術上的難題,讓我能做的更加完善。在此期間,我不僅學到了很多新知識,而且開闊了視野,提高了自己的設計能力。其次我要感謝幫助過我的同學,他們?yōu)槲医鉀Q了不少我不太明白的設計難題。感謝所有在設計中幫助過我的良師益友和同學。36Proceedings ofthe2006 IEEE/RSJ International Conference on Intelligent Robots and Systems October9- 15, 2006, Beijing, China ANovelModularFixtureDesignandAssemblySystem BasedonVR PengGaoliang, LiuWenjian SchoolofMechatronicsEngineering HarbinInstituteofTechnology Harbin, 150001, China pgl7782a Abstract - Modular fixtures are one oftheimportant aspects ofmanufacturing. This paper presents a desktop VR system for modular fixture design. The virtual environmentis designed and the design procedure is proposed. It assists the designer to make the feasible design decisions effectively and efficiently. A hierarchical data model is proposed to represent the modular fixture assembly. Based on this structure, the user can manipulate the virtual models precisely in VE during the design and assembly processes. Moreover, the machining simulation for manufacturing interaction checking is discussed and implemented. Finally, the case study has demonstrated the functionality of the proposed system. Compared with the immersive VR system, the proposed system has offered an affordable andportable solutionformodularfixtures design. Index Terms - Modularfixture, desktop VR, assembly design, machiningsimlulation. I. INTRODUCTION Modular fixtures are one of the important aspects of manufacturing. Proper fixture design is crucial to product quality in terms of precision, accuracy, and finish of the machined part. Modular fixture is a system of interchange- eable and highly standardized components designed to securely and accurately position, hold, and support the workpiece throughout the machining process 1. Tradition- ally, fixture designers rely on experience or use trial-and- error methods to determine an appropriate fixturing scheme. With the advent of computer technology, computer aided design has been prevalent in the area of modular fixture design. In general, the associated fixture design activities, namely setup planning, fixture element design, and fixture layout design are often dealt with at the downstream end of the machine tool development life-cycle. These practices do not lend themselves well to the bridging of design and manufacturing activities. Forexample, very few systems have incorporated the functionality of detecting machining interference. This leads to a gap between the fixture design andmanufacturing operationswheretheaspectofcutterpaths is not considered during the design stage 2. As a result, re- designcannotbeavoidedwhenthecutterisfoundtointerfere with the fixture components in the manufactu- ring set-up. Therefore, in orderto bring machining fixture design into the arenaofflexiblemanufacturing, amoresystematicandnatural designenvironmentisrequired. As a synthetic, 3D, interactive environment typically generated by a computer, VR has been recognized as a very powerful human-computer interface for decades 4. VR holds great potential in manufacturing applications to solve problems before being employed in practical manufacturing thereby preventing costly mistakes. The advances in VR technology in the last decade have provided the impetus for applying VR to different engineering applications such as product design 5, assembly 6, machining simulation 7, andtraining 8. The goal ofthis paper is to develop a VR- basedmodular fixtures design system (VMJFDS). This is the firststepto develop anintegratedandimmersiveenvironment for modular fixture design. This application has the advantages of making the fixture design in a natural and instructive manner, providing better match to the working conditions, reducing lead-time, and generally providing a significantenhancementoffixtureproductivityandeconomy. II. OVERVIEWOFTHEPROPOSEDSYSTEM The system architecture of the proposed desktop VR systemismodularisedbasedonthefunctionalrequirements of thesystem,whichisshowninFig.1. Atthesystemlevel,three modules of proposed system, namely, Graphic interface (GUI), Virtual environment (VE) and Database modules are designed. For each ofthe modules, a set ofobjects has been identified to realize its functional requirements. The detailed objectdesignandimplementation are omittedfromthispaper. Instead, the briefdescription ofthese three modules is given below. 1) Graphic Interface (GUI): The GUI is basically a friendly graphic interface that is used to integrate the virtual environmentandmodularfixturedesignactions. 2) Virtual environment (VE): TheVEprovidestheusers with a 3D display for navigating and manipulating the models of modular fixture system and its components in the virtual environment. As shown in Fig. 1, the virtual environment module comprises two parts, namely assembly design environment andmachiningsimulationenvironment. Theuser selects appropriate elements andputs downthese elements on the desk in the assembly design area. Then he assembles the selected elements one by one to build up the final fixture systemwiththeguidanceofthesystem. 1-4244-0259-X/06/$20.00 C)2006IEEE 2650 Authorized licensed use limited to: Nanchang University. Downloaded on December 20, 2009 at 22:44 from IEEE Xplore. Restrictions apply. Fig.1.OverviewofthedesktopVRbasedmodularfixturedesignsystem. 3) Database: The database deposit all of the models of environment and modular fixture elements, as well as the domain knowledge and useful cases. There are 5 databases shown in Fig.1. Among them, knowledge & rule base governing all fixture planning principles forms the brains of thesystem. III. PROCEDUREOFMODULARFIXTUREDESIGN In this section, an instructive modular fixture design procedure within VE is presented. Besides the 3D depth that the users feel and the real-world like operation process, this procedure features intelligence and introduction. During the design process, some useful cases and suggestion will be presented to the user for reference based on intelligent inference method such as Case based reasoning (CBR) and Rule based reasoning (RBR). Further more, relative knowledge andrules arepresented ashelppages thattheuser caneasilybrowsedduringthedesignprocess. Overview of modular fixture design process is summarized in Fig. 2. After the VE environment is initialed andthe workpiece is loaded, the first step is fixtureplanning. Inthis step, theuserfirstdecides thefixturing scheme, thatis specifies the fixturing faces of the workpiece interactively. Forhelptheusersdecision-making, someusefulcasesaswell as their fixturing scheme will be presented via the automatic CBR retrieval method. Once the fixturing faces are selected, theusermaybepromptto specifythefixturingpoints. Inthis task, somesuggestions andrulesaregiven. After the fixturing planning, the next step is fixture FUs design stage. In this stage, the user may be to select suitable fixture elements andassembletheseindividualparts into FUs. According to the spatial information ofthe fixturingpoints in relation to the fixture base and the workpiece, some typical FUs and suggestions may be presented automatically. These willbehelpfulfortheuser. AftertheplanningandFUs design stage, the next stage is interactively assembling the designed fixtureFUstoconnecttheworkpiecetothebaseplate. When the fixture configuration is completed, the result will be checked and evaluated within the machining environment. The tasks executed in this environment including assembly planning, machining simulation, and fixture evaluation. Assemblyplanning isusedto gain optimal assembly sequence and assembly path of each component. Machining simulation is responsible for manufacturing interaction detection. Fixture evaluation will check and evaluate the design result. In conclusion, the whole design process isinanaturemannerforthebenefitofVE. Moreover, the presented information of suggestion and knowledge can advise the user on how to make decisions ofthe best design selection. IV. ASSEMBLYMODELINGOFMODULARFIXTURE A. Modularfixturestructureanalysis A functionalunit(FU) is acombination offixture elements to provide connectionbetweenthebaseplate and aworkpiece 11. Generally, modularfixture structuremaybe dividedinto three functional units according to its basic structure characteristics, namely locating unit, clamping unit, and supporting unit. The number offixture elements in aFU may consist ofone or more elements, in which only one element serves as a locator, support or clamp. The major task ofthe modularfixture assembly is to selectthe supporting, locating, clamping and accessory elements to generate the fixture FUs toconnecttheworkpiecetothebaseplate. By analyzing the practical application ofmodular fixtures, it is found that the assembly ofmodular fixtures begins by selecting the suitable fixture elements to construct FUs, then subsequentlymountingtheseFUs onthebaseplate. Therefore, the FUs can be regarded as subassemblies ofmodular fixture system.Further,thestructureofmodularfixturesystemcanbe representedasahierarchalstructureasshowninFig.3. 2651 Authorized licensed use limited to: Nanchang University. Downloaded on December 20, 2009 at 22:44 from IEEE Xplore. Restrictions apply. UsefTa6 *T- siikg&Sugge lr,l Fixtui e Elemenets rUetrieval i0 Tools rKetrieval 4 Fig.2Modularfixturedesignprocedureinproposedsystem B. Hierarchically structured data modelfor modularfixture representation in VE It is common that the corresponding virtual environment may contain millions ofgeometric polygon primitives. Over thepastyears, anumberofmodel sub-division schemes, such asBSP-tree 10 andOctrees,havebeenproposedto organize largepolygonalmodels.However, formodular Ba 1I_ 1 Hsreplalte Bansepla1nte Elements *Locatng ElementsL,cating Units AccessoryEllements ClamnpingElemnents !ClampingUnits SupportingElemntsSupporting Ufnits Accessory Elements Fig. 3Hierarchical structureofmodularfixture system design applications, the scene is also dynamically changing, due to interactions. For example, in design process, the part object may change its spatial position, orientation and assembly relations. This indicates that a static representation, such as BSP-tree, is not sufficient. Further more, the above models can only represent the topology structure of fixture system in the component level. However, to the assembly relationship among fixture components, which refers to the mating relationship between assembly features that is not concerned. In this section, we present a hierarchically structuredandconstraint-baseddatamodelformodularfixture system representation, real-time visualization and precise 3D manipulationinVE. As shown in Fig.4, the high-level component based model is used for interactive operations involving assemblies or disassembles. It provides both topological structure and link relationsbetweencomponents. Theinformationrepresent- ed in the high-level model can be divided into two types, i.e. component objects and assembly relationships. Component objects can be a subassembly or a part. A subassembly consists of individual parts and assembly relationships betweentheparts. Component Level (Pt Part S Subassembly Assembly relationship Feature Level Ft3 Feature Feature mating relationship t- -t Polygon Level FZ-ll. Polygon Fig.4ThehierarchicalstructuredatamodelinVE Themiddle-levelfeaturebasedmodelisbuiltuponfeatures and feature constraints. In general, the assembly relationship often treated as the mating relationships between assembly features. Thus the featurebasedmodel isusedto describethe assembly relationship andprovides necessary information for spatial relationship calculating during assembly operation. In this model, only the feature relationships between two different components are considered. The relationship between features ofone element will be discussed in feature basedmodularfixtureelementmodelingbelow. The low-level polygon based model corresponds to the above two level models for real-time visualization and interaction. It describes the entire surface as an inter- connected triangular surface mesh. More about how the polygons organized of a single element will be discussed is thenextsection. C. Modularfixtureelementsmodeling As we know, in VE, the part is only represented as a number ofpolygon primitives. This result in the topological 2652 Authorized licensed use limited to: Nanchang University. Downloaded on December 20, 2009 at 22:44 from IEEE Xplore. Restrictions apply. relations- hips and parametric information are lost during the translation process of models from CAD systems to VR systems. However, this important information is necessary in design and assembly process. In order to fulfill the requirements, we present a modeling scheme for fixture elementsrepresentationinthissection. The modular fixture elements are pre-manufactured parts withstandarddimensions. Afterthefixturingschemedesigned, the left job is to select suitable standard elements and assemblethese elements to formafixture systeminafeasible andeffectivemanner. Therefore, intheproposed system, only the assembly features of the fixture elements need to be considered. Inthispaperanassemblyfeature isdefinedas apropertyof afixture element, whichprovidesrelatedinformationrelevant to modular fixture design and assembly/disassembly. The following eight function faces are defined as assembly featuresoffixtureelements: supportingfaces, supportedfaces, locating holes, counterbore holes, screw holes, fixing slots, andscrewbolts. Besidestheinformation aboutthefeaturelike typeanddimension, otherparameters, i.e. therelativeposition andorientationofthe featureintheelements localcoordinate system are recorded with the geometric model in the fixture element database. When one element assembles with another, the information aboutthematedfeatures isretrieved andused to decide the spatial relationship ofthe two elements. More information about the assembly features and their mating relationship arediscusseddetailedinRef 1. D. Constraintbasedfixtureassemblyin VE 1)Assemblyrelationshipbetweenfixtureelements Mating relationships have been used to define assembly relationships between part components in the field of assembly. According to the assembly features summarized in the above section, there are fivetypes ofmating relationships between fixture elements. Namely against, fit, screw fit, across, andT-slotfit,which are illustrated inFig. 5. Based on these mating relationships, we can reason the possible assemblyrelationshipofanytwoassembledfixtureelements. 2)Assemblyrelationshipreasoning Ingeneral, the assemblyrelationship oftwo assembledpart isrepresented as thematedassembly featurepairs ofthem. In the above section, we defined five basic mating relationships between fixture elements. Therefore, it is enabled to decide the possible assembly relationships through finding the possible mating assembly feature pairs. These possible assembly relationships are saved in assembly relationships database(ARDB)forfixtureassemblyinnextstage. However, when the fixture is complicated and the numbers ofcomposite fixture elements is large, the possible assembly relationships are too much to take much time for reasoning andtreating. To avoidthis situation, wefirstdecide the possible assembled elements pairs. That is to avoid reasoning the assembly relationship between a clamp andthe baseplate, for they never were assembled together. In this stage, some rules are utilized to find the possible assembled elementspairs. The algorithm of assembly relationships reasoning is similar to what discussed in Ref 12. Thus the detailed descriptionofthealgorithmisomittedfromthispaper. (a) AIlai.ns .2 l.I.F LIi I7 F d) Asicmie 1f-isxkt Elmn Fig. 5Fivebasicmatingrelationshipsbetweenfixtureelements 3)Constraint-basedfixtureassembly Aftercarrying outthe assemblyrelationships reasoning, all possible assembly relationships ofthe selected elements are establishedandsavedinARDB. Basedontheserelationships, the trainee can assemble these individual parts to a fixture system. This section is about the discussion of interactive assembly operation in VE. The process ofa single assembly operation is presented in Fig.5 and illustrated by two simple partsassemblyasshowninFig.6. In general, the assembly operation process is divided into three steps, namely assembly relationship recognizing, constraint analysis and applying, constraint-based motion. Firstly, the trainee selects an element and moves it to the assembled component. Once an inference between the assembling and assembled component is detected during the moving,the inferredfeatures is checked. Ifthetwo features is one of the assembly relationships in ARDB, they will be highlighted and will await the users confirmation. Once it is confirmed, the recognized assembly relationship will be appliedby constraint analyzing and solving, that is adjustthe translationandorientationoftheassemblingelementtosatisfy the position relationship ofthese two components, as well as applythenew constrainttotheassemblingelement.Whenthe new constraint is applied, the motion of the assembling element will be mapped into a constraint space. This is done bytransferring 3Dmotiondatafromtheinputdevicesintothe allowable motions ofthe object. The constraint-based motion notonlyensuresthattheprecisepositionsofacomponentcan be obtained, but also guarantee that the existing constraints will not be violated during the future operations. The assembling element will reach to the final position through succession assembly relationship recognizing and constraint applying. 2653 Ii 1-11 4- (b) F.t Authorized licensed use limited to: Nanchang University. Downloaded on December 20, 2009 at 22:44 from IEEE Xplore. Restrictions apply. NO Assembly relationship Iis possible checking elatioohship? Fig. 6Processofassemblyconstraintestablishment No V. MACHINING SIMULATION A. Manufacturinginteractions During the machining process, there are many types of manufacturing interactions associated with the fixture may occur. These interactions can be divided into two broad categories illustrated below, namely static interactions and dynamicinteractions. 1) Static interactions refer to the interference between fixture components, the interference between fixture components and machine tool, and the interference between fixture components andmaching feature ofworkpiece during theworkpiecesetup. 2)Dynamicinteractionsrefertothetool-fixtureinteractions, which occur within a single operation when the tool and the fixtureusedinthatoperationmaycollideduringcutting. Generally, the aspects of machining process and cutter paths are not considered duringthe fixture design stage. As a result, these interactions may often occur during the practical manufacturing. Thus the human machinists have to spend muchoftheirtimeidentifyingtheseinteractions andresolving them. Itis oftenresults inmodification orre-designoffixture system. Thatistediousandtimecostly. B.Interferencedetection Although the currently commercial software, like VERICUT, can simulates NC machining to detect tool path errors and inefficient motion prior to machining an actual workpiece. It is available to eliminate errors that could ruin the part, damage the fixture, break the cutting tool, or crash the machine during the part programming stage. However, these software are expensive and oriented to NC program- mertherebynotsuitableforfixturedesigners. During the fixture design stage, it should be ensured that the associated fixture interactions can be avoided. In this system, after the fixture configuration is complete, the machining simulation module is presented to the user to identifytheinteractionsandresolvethem. Within the machining simulation environment, the 3D digitalmodelofmachinetoolispresented. The canassemble the fixture components on the work bench and setup the workpiece, just as what the machining engineers do in the actual site. During the setup, the fixture components and the workpiece are move to their assembly position under manipulation. Theinterferencecheckingmoduleiscarriedout. Ifinterference occurs, the inferred objectwill be highlight. It is p
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